They are 29 Chev wheels crudely adapted to T hubs. 1928 Chev wheels were 21". 29 Chevs are 20". They are not special speedster wheels. If you look you can see the original Chev lug nut holes in between the T holes.

For the front you can put the Chevvy spindles of '27-28 right onto the T axle. '28 rims are wider than '27 but will interchange. I don't see the use in making adapters, just redrill to fit the T hubs. Adapters also set the wheel out a bit giving a wider track. The outset of the tire foot print from the kingpin starts getting you into a situation where the car is harder to keep it tracking straight without wanting to wander side to side.

Aaron, I do it your way, I just redrill and bolt on. I use a spacer on the inside to bring the disk out a little to the width that a ford wheel would be located at. The original outside ring from a wood spoke wheel makes a good cover for the extra Chevy bolt holes. It looks good but maybe not show quality, but I hate shows so I am happy with the looks.

Willie and Aaron the reason for the adapters , 1)as Willie mentioned the tracking needs to be 1/2 inch wider on each side as opposed to directly bolting the wheel to the hub, in order to maintain the original tracking , 2) to support the wheel at the hub, to relieve some stress on the bolt holes when sideways pressure is applied to them in a corner, all the research I found stated to watch for cracks in the rim or hub 3) my adapters won't break , I can bolt on a new wheel or hub in minutes